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胶州湾夜光藻种群动态及其摄食特征研究
田达玮
学位类型硕士
导师李才文
2017-05-12
学位授予单位中国科学院大学
学位授予地点北京
学位专业环境科学
关键词夜光藻 种群动态 繁殖 摄食 生态效应
摘要本研究于2015年逐月对胶州湾12个站位进行了多学科综合调查,获取了胶州湾红色夜光藻(red Noctiluca scintillans)种群以及水文、生化等环境因子的周年数据,分析了环境因子与夜光藻的种群动态间关系,探讨夜光藻大量繁殖的生态学机制;并通过综合分析夜光藻种群动态与浮游植物周年数据、夜光藻摄食实验数据,研究夜光藻的摄食行为,以评估夜光藻大量繁殖时对浮游生物群落可能造成的影响。主要结论如下:
(1)夜光藻丰度、有性和无性繁殖个体比例的月际变化显著。全年各站位夜光藻丰度范围为0~31.37×103 ind./m³,月平均丰度呈现双峰分布,峰值分别出现在2月和7月。二分裂个体比例介于0~31.25 ‰,有性繁殖个体比例介于0~29.41 ‰,两种繁殖方式均呈现出季节差异及站位差异,表明这两种繁殖方式均受环境因素的影响。在浮游植物丰度降低时,有性繁殖和二分裂个体比例均出现下降,而当浮游植物丰度回升时,有性繁殖比二分裂更快的响应食物恢复。
(2)水温、叶绿素a、亚硝氮和硝氮是影响夜光藻种群动态的主要环境因子。夜光藻是冷水种,且高温会抑制夜光藻的二分裂,因此水温与夜光藻种群丰度、两种繁殖个体比例均呈显著负相关关系;夜光藻的生长繁殖需要充足的食物来源,浮游植物丰度和叶绿素a浓度反映夜光藻食物的丰富程度,因此与夜光藻丰度、两种繁殖个体比例呈显著正相关;亚硝氮和硝氮可能对夜光藻代谢、繁殖起调控作用,与夜光藻丰度及有性繁殖个体比例呈负相关。
(3)链状硅藻是胶州湾海域夜光藻的主要食物来源之一。对2015年浮游植物周年样品和夜光藻丰度间相关性分析发现,夜光藻丰度与链状硅藻丰度间呈极显著正相关关系,表明在野外链状硅藻可能是夜光藻最主要的食物来源。链状硅藻与浮游植物多样性指数呈显著负相关关系,表明链状硅藻的丰度升高会导致浮游植物多样性下降,同时可能增加夜光藻赤潮暴发的潜在风险。
(4)夜光藻的摄食行为具有食物选择性。夜光藻的室内摄食实验结果显示夜光藻对饵料藻的摄食率和含食物泡个体比例均随饵料藻密度的升高而升高。对中肋骨条藻和青岛大扁藻的摄食率整体高于对其他藻类的摄食率,对红色赤潮藻的摄食率最低。受饵料藻细胞表面性质和运动能力影响,夜光藻对硅藻的摄食率及含食物泡个体比例随饵料藻细胞体积的增大而增大,对甲藻的摄食率及含食物泡个体比例随饵料藻细胞体积的增大而减小。
(5)夜光藻摄食能够显著影响浮游生物群落结构。夜光藻的现场摄食实验发现夜光藻的摄食使得硅藻和甲藻丰度均出现显著降低,但链状硅藻的下降比例远高于非链状硅藻和甲藻。实验组链状硅藻中圆海链藻和双突角毛藻丰度下降比例分别达到71.42 %和64.58 %,而实验组中多种甲藻的丰度高于对照组。经过夜光藻摄食,实验组的硅藻/甲藻比例比对照组下降29.18 %,非链状硅藻/链状硅藻比例提升43.34 %。表明链状硅藻更容易被夜光藻捕获,夜光藻的摄食可能在短时间内改变浮游植物群落结构,影响浮游生物群落间的营养传递。
其他摘要To investigate the mechanism of Noctiluca scintillans blooms in the Jiaozhou Bay, water samples were collected in 12 stations from January to December, 2015. Correlation among population dynamics, population structure, and environmental factors were studied. The correlation between N. scintillans aboudance and annual variation of phytoplankton data, and grazing behavior of N. scintillans in both laboratory experiments and field experiments was also analyzed to investigate its affects on phytoplankton communities. The major findings were listed as following:
(1) Inter-monthly variation was founded in the abundance of N. scintillans and the ratio of reproductive individuals. The abundance of N. scintillans varied from 0 to 31.37×103 ind./m³, and the average monthly abundance presented a bimodal distribution pattern, peaks appeared at Feburary and July. The ratio of binary fission was between 0~31.25 ‰, and the ratio of sexual reproduction was between 0~29.41 ‰. There were overt seasonal and spatial variations in the ratios of sexual reproduction and binary fission, indicating that the two reproduction strategies were affected by environment factors. The ratios of the two reproduction strategy decreased along with decreasing of phytoplankton abundance, the sexual reproduction responded faster than the binary fission when the abundance of phytoplankton risen again.
(2) Water temperature, chlorophyll a, nitrite and nitrate were the key factors influencing the abundance and reproduction of N. scintillans. Water temperature was negatively correlated with the abundance of N. scintillans and the ratio of reproductive individuals. Chlorophyll a was positively correlated with the abundance of N. scintillans and the ratio of reproductive individuals, since chlorophyll a indicates the abundance of food for N. scintillans. Nitrite and nitrate were negatively correlated with the abundance of N. scintillans and the ratio of sexual reproduction, indicating that nitrite and nitrate might play an important role in regulating the metabolism pathway of reproduction.
(3) Chained diatoms might be the major food source for N. scintillans in Jaozhou Bay. The abundance of N. scintillans was positively correlated with the abundance of chained diatoms, suggested the chained diatoms might be the major food source for N. scintillans. The abundance of N. scintillans were negatively correlated with the Shannon-Wiener index, indicating the decrease in diversity of phytoplankton might increase the risk of N. scintillans bloom.
(4) N. scintillans had overt food preference in laboratory trials.The laboratory experiment indicated the grazing rate and the proportion of indvidals containing food vacuoles increased with increasing bait concentration. The grazing rates on Skeletonema costatum and Platymonas helgolandica Kylin var. tsingtaoensis were higher than the others. The grazing rate on Akashiwo sanguinea was the lowest. Grazing behavior was affected by the surface property and mobility of different baits. As to diatoms and Platymonas helgolandica Kylin var. tsingtaoensis, the grazing rate and the proportion of food vacuoles was positively correlated with the cell volume, while the results were in the opposite for dinoflagellates.
(5) The grazing of N. scintillans impacted the structure of plankton community. The grazing of N. scintillans in field water caused decreasing in the abundances of both diatoms and dinoflagellates. The decreasing in chained diatoms was higher than the decreasing in unchained diatoms. The abundance of Thalassiosira rotula and Chaetoceros didymus decreased more than 50 %, with higher abundance of dinoflagellates in experiment group than control group. The ratio of dinoflagellate/diatom and unchained/chained diatoms in the experiment group were 43.13 % and 43.34 % higher than the control group. The results indicated the chained diatoms are more likely to be grazed by N. scintillans and the grazing of N. scintillans will change the structure of phytoplankton community in short period.
学科领域海洋科学
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/136560
专题海洋生态与环境科学重点实验室
作者单位1.中国科学院海洋研究所
2.中国科学院大学
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田达玮. 胶州湾夜光藻种群动态及其摄食特征研究[D]. 北京. 中国科学院大学,2017.
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